Vector loop RAIM in nominal and GNSS-stressed environments

The performance of a receiver autonomous integrity monitoring (RAIM) algorithm for vector tracking receivers is evaluated. Both nominal and degraded signal environments are considered. Given the same receiver hardware components (i.e., front end electronics and crystal oscillator), it is shown that vector loop RAIM produces lower protection levels than scalar loop RAIM. Thus, vector RAIM has the potential to improve availability, especially in degraded signal environments. However, the performance of vector loop RAIM is sensitive to the distortions of the correlation peak (caused, e.g., by multipath), which may affect its ability to detect faults.